fix(scanner): move RemoveImmutableScanners before EnsureScanners (#12957)
fix(scanner): move RemoveImmutableScanners before EnsureScanners (#12957)

RemoveImmutableScanners may delete the default scanner, so move it
before the EnsureScanners.

Closes #12938

Signed-off-by: He Weiwei <c834efa4898f8bf976e231f3903babf913725c68@vmware.com>
wy65701436/harbor,reasonerjt/harbor,reasonerjt/harbor,reasonerjt/harbor,wy65701436/harbor,reasonerjt/harbor,wy65701436/harbor,reasonerjt/harbor,wy65701436/harbor,wy65701436/harbor,reasonerjt/harbor,wy65701436/harbor